As is well known, the human lens of the human eye may have a decrease in characteristics such as modulation ability, transparency and the like due to aging, disease or the like, and along with that, problems such as refractive error, cataracts or the like occur and visual performance decreases. As a treatment for such cases, an intraocular lens has been proposed from the past. This intraocular lens is typically inserted within the capsule in place of the human lens after the intracapsular human lens of the human eye is extracted and removed.
However, for the intraocular lens of the conventional structure, the spherical lens power is set, and an intraocular lens of a spherical lens power suited for the patient was selected and used considering the corneal curvature, ocular axis length and the like.
However, even when an intraocular lens suited for the patient is used, there were complaints such as, “It's hard to see,” “I can't see objects well,” and the like from patients who had the intraocular lens inserted. This kind of vision problem refers to quality of vision (QOV), and in recent years, has been found to be due to residual irregular astigmatism. Residual irregular astigmatism is due to high-order aberration of the human eye, and this cannot be corrected with conventional lenses for visual correction that correct vision using the spherical lens power and the cylindrical lens power such as intraocular lenses, glasses, or contact lenses.
To handle this kind of problem, to reduce high-order aberration in the human eye, in Japanese Patent No. 4459501 (Patent Document 1), proposed is an intraocular lens that gives wave aberration of the reverse code value to the wave aberration in the human eyes of a specified population. However, with this intraocular lens, it was difficult to say that an efficient method had been established regarding selection of the specified population, measurement of the wave aberration, setting of the reverse code value wave aberration to the intraocular lens and the like, and putting this to practical use was extremely difficult.
Specifically, as with the description noted in Patent Document 1, prescribing for the intraocular lens optical characteristics for which reverse code value high-order aberration is set so as to offset the high-order aberration of the human eye to become zero maybe ideal, but making this practical is extremely difficult. Perhaps because in addition to the fact that there are diverse high-order aberrations with the human eye, coma aberration and the like which has a particularly big adverse effect on quality of vision (QOV) has different optical characteristics around the optical axis, so the intraocular lens set with a high-order aberration for correction must be a custom made product, and not only the design but also the manufacturing of these is extremely difficult and impractical.
Though it relates to contact lenses of a different technical field than the intraocular lens that is the subject of the present invention, noted in Translated Japanese Patent application of Publication No. 2006-517676 (Patent Document 2) as a method of improving the QOV in relation to residual irregular astigmatism is the provision of a corrective lens that uses a chart for which the level of effect on the QOV is actually measured for each order of the high-order aberration expressed by Zernike polynomials, the orders of high-order aberration important for improvement of QOV is specified, and the specified high-order aberrations are offset to achieve zero. However, with this Patent Document 2, as noted in paragraphs [0097] to [0099], this is nothing more than the goal of selecting only the specified high-order aberrations that adversely affect vision, and giving a corrective lens that offsets the selected specified high-order aberrations to achieve zero. Based on examination by the inventor of the present invention, with a corrective lens power that makes only the specified high-order aberrations zero in this way, the adverse effect on vision due to other residual high-order aberration is large, and it was difficult to obtain sufficient QOV improvement effect.
In particular, with this method noted in Patent Document 2, when a corrective lens is provided with a plurality of orders of high-order aberrations as the subject, and all of those high-order aberrations are offset to reach zero, the corrective lens design and manufacturing are extremely complex and they have to be made to order, so they are not very practical, and the same kinds of problems as those of Patent Document 1 are unavoidable. Meanwhile, when providing a corrective lens that has only one high-order aberration (e.g. spherical aberration) as the subject and offsetting that to reach zero, the adverse effect due to other remaining high-order aberrations (e.g. coma aberration) is large, and it was difficult to realize good vision.